This project proposes to test adaptations of the Diabetes Prevention Program (DPP) designed to increase the likelihood of widespread use in workplace settings. DPP, which has been proven efficacious in clinical trials, is a six month weight management program designed to reduce caloric intake and increase caloric expenditure. As a clinic- based intervention, the original DPP intervention was tested on a high risk (pre-diabetic) target group using frequent one-on-one contact to achieve change, a model that is not generalizable to a broader population or non-clinical settings. In this study, we will determine a) if a moderate intensity adaptation of DPP can be efficacious, b) the comparative effectiveness of two intervention modalities - telephone and group, and c) the incremental cost-effectiveness of the interventions. The participating sites are two city/county governments with over 4500 employees. Participants will be randomly assigned to one of three intervention conditions: telephonic coaching and manual, group coaching and manual, and manual alone. The intervention manual that underlies all three interventions is the same as DPP. The primary outcome measure is BMI with secondary outcomes of healthy eating behaviors and physical activity. An incremental cost-effectiveness analysis will be conducted comparing each intervention to one another. Data will be collected at baseline, posttest (six months), and follow up (12 months). The hypotheses will be tested using a growth modeling approach examining changes over time. This will enable us to maximize the translation of DPP across worksite populations by using approaches which are realistic for most work organizations.